But for half a decade in the 1980s, Black was also Jonas Savimbi's man in the capital city. His lobbying firm received millions from the brutal Angolan guerrilla leader and took advantage of Black's contacts in Congress and theWhite House.

Justice Departmentrecords that Black's firm submitted under the Foreign Agents Registration Act detail frequent meetings with lawmakers and their staffs and lavish spending by Black and his partners as they attempted to ensure support for Savimbi, whose UNITA movement was fighting the Marxist Angolan government.

Then in his 30s, Black already had established himself as a pioneer of the revolving door between campaign consulting and lobbying, having been a senior adviser on PresidentRonald Reagan's reelection campaign before returning to K Street. And his clients, as often as not, were foreign leaders eager to burnish their reputations.

In addition to Savimbi, Black and his partners were at times registered foreign agents for a remarkable collection of U.S.-backed foreign leaders whose human rights records were sometimes harshly criticized, even as their opposition to communism was embraced by American conservatives. They included Philippine PresidentFerdinand Marcos, Mobutu Sese Seko of Zaire, Nigerian Gen. Ibrahim Babangida, Somali President Mohamed Siad Barre, and the countries of Kenya and Equatorial Guinea, among others.

That client list is now the subject of a fierce attack from Democrats who are clamoring for Black, 60, to be fired as McCain's top political strategist. And the candidate's decision this month to impose a strict ban on lobbying for foreign governments by members of his staff has only intensified the scrutiny of Black's past.

McCain "portrays himself as Mr. Clean, and then he has all these lobbyists around him who are connected to a lot of not-so-clean people," saidPaul C. Light, a professor of public service atNew York University. "One of the things Obama will do is portray him as the creature of Washington, and what could be more Washington-esque than having a dictator as a client?"

The back-and-forth between lobbyists and presidential advisers is not exclusive to Republicans. Democratic candidateBarack Obamadoes not accept donations from lobbyists, but the senator from Illinois has lobbyists informally advising him on strategy and on policy.

Black has retired from lobbying, having left BKSH & Associates recently. But he says he has no intention of leaving the campaign and is unapologetic about a lobbying career spanning 30 years and seven presidential campaigns. He said his firms never represented foreigners "without first talking to theState Departmentand the White House and clearing with them that the work would be in the interest of U.S. foreign policy."

For instance, he said, the United States considered Marcos an ally when Black's firm took on work for the Philippine government, and "when the White House pulled the plug on Marcos, we resigned the account the same day." He said his firm was hired to help show Mobutu how to form political parties and conduct elections, and when Mobutu canceled the results of a parliamentary election, "we quit."

"Anyone that knows John McCain and his record understands that he's a public servant who stands on principle. Any suggestion otherwise isn't rooted in fact," said Tucker Bounds, a spokesman for the campaign. But McCain has long been seen as a fighter against just the kind of special interests that paid Black handsomely.

Black formed the political consulting firm Black, Manafort and Stone in 1980 with two other Republican political advisers, Paul Manafort and Roger Stone. In 1981, the trio started a separate lobbying company by the same name. In subsequent years, the lobbying firm added Democrat Peter Kelly, and the consulting firm tapped legendaryGOPadviser Lee Atwater.